QA402 Accumulating Traces on a Plot

QA40x
21

I was wondering if there was some way to have the AMP FREQ Response Chirp Automated test to use the dBr settings from the normal Frequency Response Test or have an offset applied. For example, this is a plot of the effect of the tone controls for an Integrated amp.

Tone Controls
Tone Controls918×610 79.8 KB

In this case I was running the amp such that it has a fair amount of gain. True, for the sake of just showing the effect of the tone controls I could have set the amp for 0dB of gain, but I did not figure that out until later and figured there could be other instances where I would like to have some offset applied so that I the center of the graph was at Zero (or some other point as the case may be)… Maybe that capability exits, but I could not find it…

22

Hi @Var, I don’t think it can be done right now. But as with the other plug-ins, I think it would be valuable to have “Plot as Gain” as a checkbox for this plugin. I will make sure this gets added in the coming weeks. I remember looking at guitar pedal EQs a while back and running into the same issue.

BTW, that is a cool plot that readily reminds us all the real world isn’t as precise as we might imagine.

23

Thanks for the reply Matt.I am not sure plot as gain would get me what I wanted unless you could offset it… I did watch the guitar pedal eq video to see if there was something there that would help. When I measured the LOUDNESS control (which has 2 settings), I made sure the unit was set for close to no gain. Probably should have changed the title of the vertical axis to Gain:

loundess
loundess907×579 76.8 KB

24

Hi @Var, yes, you are right the current behavior is “plot as gain” and so when that is NOT checked, it would be in a REL mode, with REL being established at the start of measurement using a 1 kHz tone.

1 Like
25

Hi @Var, I just double checked and the stepped tones plug-in already has a “plot as gain” checkbox. That should let you normalize your EQ response.

image

If you enable that, the gain at each step will be computed and plotted. Please try and see what you think.

26

Thanks for the update- I just plotted several tone control responses yesterday, but adjusted the receiver and qa402 output to get around 0dBv for the flat response, but will try the plot as gain function the next time I have the opportunity. BTW, I love my QA402!

27

Edit: I figured it out.

28

@matt It isn’t all figured out. I want to save measurements to compare them in the Graph Tool. All I seem to be able to save is bitmaps and EMF files. Is the only way to save a CSV to use Tractor?

My typical use case is working on a single unit. Measure - tweak - measure - compare a to b - tweak - measure …
And also to compare a measurement done 3 weeks or months ago to the same unit or another one.

29

Hi @THDaniel, When you have a trace you like, export it via the Traces-> Export Trace.

Later, when you want to compare to that trace, pull it back in via Traces->Import Trace

image

There’s also a work item to do multi-trace export. This would make sense if you want to pull all the traces into Excel.

30

That didn’t work. When I run a measurement and open Graph Tool → Traces, everything except Import Trace is greyed out.
Currently I am running 1.181, Graph Tool window says “Graph 269”.

31

Ok, I think I got it now. I need to run the measurement from the “Automated Test” dropdown menu.